Make a pistachio pudding Bundt cake by beating together 1 box of white cake mix, 1 package of pistachio pudding mix, 4 eggs, 1/2 cup of orange juice, and 1/2 cup each of water and vegetable oil. Spoon 3/4 of the mixture into a greased Bundt pan. Whisk 3/4 cups of chocolate syrup with the remaining cake batter, and pour it in the pan. Lightly mixing the batters using a knife, and bake the cake 350 F for one hour.
Use a different recipe to make a pistachio Bundt cake by whisking together 1/4 cup of granulated sugar, 1/4 cup of brown sugar, 1 teaspoon of ground cinnamon and 1/2 cup of finely chopped pistachios in one bowl and beating 1 box of yellow cake mix, 1 3.4-ounce package of instant pistachio pudding, 4 eggs, 1 cup of sour cream and 1/2 cup of vegetable oil in another bowl. Stir 1 teaspoon of almond extract into the cake batter, and pour 1/3 of it into a greased Bundt pan. Sprinkle the sugar and nut mixture over the cake batter, and pour the rest of the batter over it. Bake the cake at 350 F for 50 minutes.
Meanwhile, beat together 1 cup of powdered sugar, 1/4 teaspoon of ground cinnamon, 1/2 teaspoon of almond extract, 1 tablespoon of softened butter and 2 tablespoons of milk. Drizzle the icing over the cooled cake, and sprinkle it with 1 tablespoon of finely chopped pistachios.